package CollectionDemo;

import java.util.HashMap;
import java.util.Hashtable;

public class MapDemo {

    public static void main(String[] args) {
        HashMap hashMap = new HashMap();
        hashMap.put(null, null);
        System.out.println(hashMap);
        Hashtable hashtable = new Hashtable();
        //hashtable.put(null, 1);
        hashtable.put(1, null);
    }
}
